Delete Email Subscribers (JetPack)

I’d like to remove all the email subscribers that have subscribed through JetPack’s Subscription Widget. I’ve removed the widget but the scribers remain. I’ve been searching for a way to do it myself but there appears to be none. I can’t even see that the data is held within the site’s database???

Would you please advise how this can be done? My blog site is: raygates.me